盾构直接切削大直径桩基的掘削参数研究

Study on shield cutting parameters when cutting big diameter piles

以苏州地铁盾构切削14根大直径桥梁群桩工程为依托,通过理论分析和开展盾构切削Φ1200钢筋混凝土桩基现场试验,系统研究掘削参数的变化特征和影响因素,并提出相应的掘削参数设置与控制方案。研究表明:刀盘切桩乃非全断面切削,实际切桩刀数呈现显著的波动性,是推力、扭矩变化特征的主控因素;推力、扭矩平均值与桩身宽度成线性正比相关,与桩基偏移距离总体呈反比减小趋势;由于切桩时推速、推力、扭矩均波动较大,盾构应增配小流量低速推进泵;作用于桩身的纯切桩推力、纯切桩扭矩仍近似与刀盘切深成线性正比关系。实践表明:在合理掘削参数下,盾构连续切削多根钢筋混凝土桩基是可行的。

Based on the construction of shield cutting of 14 big diameter bridge piles in Suzhou subway, the variation characteristics and influence factors of cutting parameters are studied systematically by theoretical analysis and the field test of shield cutting Ф1200 reinforced concrete piles. Corresponding setting and control method of cutting parameters is proposed. The research results show that actual cutting number has obvious fluctuation because of non full-face cutting feature of cutterhead cutting pile, and actual cutting number is the main influence factor of variation characteristics of thrust and torque. The average value of thrust and torque is directly proportional to pile width, and the thrust and torque decrease generally when pile offset distance increases. Due to the great fluctuation amplitude of advancing speed, thrust and torque, a hydraulic pump of small flow should be configured in addition. The thrust and torque acting on the pile are approximately linear with the cutterhead penetration. The Suzhou engineering practice indicates that it is feasible for shield to cut big-diameter reinforced concrete piles continuously when the cutting parameters are resonable.